Custom Sensor Wing

The off the shelf Feather/Wings provide the computing power, wifi,  timekeeping, and status display (which isn't really needed but is nice while working on the software). What's missing is inputs to the system. Specifically knowing when someone is in the room and how light/dark it is in the room.  I use this combined with the time of day to figure out how to control the lights.

For motion sensing I use a basic PIR. For light measurement I use a simple CdS photocell in a voltage divider.

There are already excellent learning guides on photoresisters and PIRs so I won't redo them here.

Notice that I'm also using a NeoPixel. This I'll use as an at a glance status indicator since the wifi Feather M0 doesn't have a Dotstar. Even if it did, the Dotstar could easily be covered depending on how the boards are stacked.

As usual, I started with the lower profile components: the NeoPixel breakout and the photocell voltage divider. Keep in mind that the photocell has to be clear of the PIR and able to "see" the ambient light.

I replaced the header pins on the PIR with longer ones that would reach past the capacitors and into the holes on the proto wing.

The PIR fits neatly between the photoresistor and neopixel.

For this one-off unit I did simple point to point wiring, largely on the underside of the board.

Last updated on Feb 19, 2018 Published on Feb 14, 2018